Metallurgical furnace



F..'A. FAHRENWALD METALLURGI CAL FURNACE Filed Junge 17, 1929 2 Sheets-Sheet 2 NWT 111 11111111 111 111 111 1111111 11 1111/ 1 1 11 1111 11111111 11 111 11 1 /111111111/11 1 11 111111/11111 11 1111r /1 11.1111/1 1 1111111111 11/1 1 ,111111111101111 111111111111111 1 1 1 11 1 1 11 1/1 1111 111 111111 11 1111/ 111/1911111117111 1011 1 11H 11711 117/111 /1 1111 111111 f 1111/1/ 111/1h11 f 1111111/ 1 11 L 1 111/1 111111 III /1 111 I /1/111 1 1111/ l/ 1 111111 l/f/l/ x 1111101 1 1 Q NN N 11H/11111 1 1 1 11 1 1 11H/1111111.14111 11n/1 11/ 11 11 11111 11 1111 1 1111111 /1 11 111/1111111111111111111 111 1111111n1111111/1 11111 l l f IPatented Oct. 27, 1931 FRANK A. FAHBENWALD, 0F CHICAGO, ILLINOIS METALLURGICAL F'UBNACE Application filed .Tune 17, 1929. Serial No. 371,613.

cludes amon its objects and advantages a decrease in up eep expense and improved fue] economy in the operation of conveying equipment and furnaces of the types commonly employed for the heat treatment of metals.

' In the accompanying drawings:

Figurel isa partly diagrammatic longi- 'tudinal section of a furnace according to the lo invention. l Y,

Figure 2 is a section on line 2--2fof Figure 1, an

Figure 3 is aside elevation of the power transmission. ln the embodiment of the invention selected for illustration, the furnace comprises the usual chamber 10. Heat may be generated inside the chamber by the usual flame projecting devices throwing flames through' openings 4,12, the products of combustion being allowed to leak or flow out of the chamber gently at the charging and delivery openings. or mouths.

c afweging" f To' subject fan object .to heat treatment in such a furnace, it is inserted at one end of the chamber and conveyedl slowly to the "other end where lit is removed. I have illustrated a conveyor made up of a chain or strand 14 running over sprockets 16, with its upper reach supported by a guide 18, over which the strand slides. This makes it possible to give each piece of metal substantially identi-I tion or the material being handled introduce material quantities ofsulphur I prefer to employ an alloy containing more than 50 chromium and less than 1,0% of nickel, be-

My invention relates to metallurgy, and inl cause the higher percentages of nickel are yaccompanied by susceptibility to corrosion by sulphur-containing compounds.

The operating temperatures I employ are all in a range Where ordinary steel and cast iron have insufficient physical strength or resistance to chemical reaction with the gases or other materials present to be capable of use. v i

I have designated the charging, or receiving end 20 and the delivery end 22. The sprockets 16 are both Within the chamber, so' that all parts of the chain and sprockets remain continuously throughout a run at the temperature prevailing inside thev chamber, and are only cooled and reheated when the outfit is shut down.

The temperatures' employed in many such chambers are limited only by the ability of the conveyor `to endure them. Recent improvements in this 'art call for temperatures v from' 17'00 to 2000 degrees,Fahrenheit in order'to impart the desired quality to the treated product. At such temperatures the mechanical strength of the best available metal is reduced to a point where the weight of the conveyor per unit length may approximate or even exceed the weight of the material carried by it. The heat lost by Jconveyor' metal moving out of the chamber is saved by keeping the strand inside, and at such high temperatures this saving isy a substantial fraction of the heat required to run a furnace. 1

At such extreme temperatures, also, the repeated heating and coolingof the strandl becomes a factorin determining the life of the strand, of substantially as much importance as any other, not excluding the usually dominating feature of mechanical wear. Keeping the strand inside substantially eliminates this item.

Charging and delivering When the material to be treated is in the form of a large number of small pieces, the chain links may be provided with carrying pans or trays 24. The material may be poured in continuously or at frequent intervals down a stationary chute 26, and received when it falls ofi the conveyor on a similar chute 28 which may guide it directly into a quenching bath 30. v

. When the material is in pieces of a size calling for individual handling, the new stock may be brought up to thev charging mouth on a roller conveyor 32 and pushed off the charging conveyor 32 on to thefurnace conveyor. I have illustrated sectional metal rails 34embedded in the upper surface of the lower wall 36 defining the charging mouth. The entering piece, when it is too short to bridge the gap between the roller conveyor and the furnace conveyor, may slide a little on these rails instead'of on the refractory material of the wall 36. v At the delivery end, pieces calling for individual handling `may be similarly pushed along over rails 38 onto a receiving conveyor 40.

With either large or small pieces, most of the charging and delivery mouths should be prevailing, the strength of the chain in creases much more rapidly than the tension.

The main item of Vtension in the chain is that developed by dragging the load over.the skid 18. A serious addition to this tension would be the'tension developed in dragging lthe return reach 46 over the sln'd 44.

sible to relievethe load at the point 62 still further by pushing a little on 'the chain at the. receiving end to carry a material fraction of the friction load on the track 18.

covered to hold the heat. I have illustrate'd\` I have indicated a4 worm Vwheel 64 and cover plates 42 of refractory material. When the operation is continuous, an orifice just large enough to provide reasonable clearance for the stream of material may be left open at each end. In the case of a furnace, it is not diiiicult to fire the furnace in such a way that the How of the products of combustion out through such orifices will prevent heat loss other than the always unavoidable y radiation loss.

When the charging and delivery are intermittent, the guide chutes 26 and -28may be withdrawn. and the covers 42 may be moved out of the way each time a piece is to be inserted or removed.

Dri/ve I have illustrated transverse shafts 48 v.which may be of the type disclosed in my Patlports 54 and may be adjusted longitudinally of the furnace by suitable means, such as rods 56 provided with adjusting turn-buckles -58 anchored at 60 to any suitable stationary anchorage. This adjustment means .makes it possible to keep the amount of slack in the chain properly adjusted. Then the chain is hot it ,should run in some such position as indicated in Figure 1, with the weight of most of itsl lower reach carried by the track v, 44, and the turn-buckles may be adjusted to secure the proper operating condition.

.Whenever the furnace is shut down and the chainl cools, the thermal vcontraction will shorten the chain and lift somewhat more of the return reach of the'chain off the track` 44. This will somewhatincrease the tension l in the chain, but at the lower temperatures 'chain 70 transmits power to'the shaft 48 at the receiving end and is automatically maintained under constant predetermined tension by passing this reach of the chain over fixed idlers 72 and under' a floating idler 74 carrying weights 76 hung on al clevis 78. In this way, by properly adjusting the weights 7 6, the force applied to/the sprockets at the receiving endis'maintained substantially co'nstant, regardless of the speed, and may be adjusted by varying the weights at 76, to any desired value.

Without further elaboration, the foregoing will so fully explain the gist ofV my invention that others may, by apply ing knowledger curl rent at the time of application, readily adapt the same for use under various conditions of service. t

I claim:

1. Highl temperature equipment comprising a hot chamber; an endless strand of heat resisting alloylin said chamber; said chamber* enclosing all of said strand; said strand including carrying means adapted to receive and support either individual large pieces of material or ay stream of small lpieces /of material; said chamber having an intake mouth and a delivery mouth adj acentthe ends of said strand; charging means at the intake mouth for delivering streams of small pieces of material, or for intermittently charging individual large pieces of material far enough through said mouth to get onto said strand;

'and receiving means for getting material ca rried through said furnace by said strand out through said delivery mouth.

2,. High temperature equipment comprising a hot chamber; transverse shafts inside said chamber at the'endsthereof; an endless conveyor strand of heat resisting alloy passing around'both shafts; a track for each reach of said strand on which said strand l may slide; a firstpower transmission for driving the shaft at the delivery end of said strand; a. second power transmission for delivering power to the shaft at the receiving end of said strand; means for adjusting the transmission to the receiving end to deliver a predetermined force or torque; and automatic means for maintaining said force or torque constant; said second power transmission being driven from said first power transmission.-

31 High temperature equipment comprising a hot chamber; transverse shafts inside said chamber at the ends thereof; an endless conveyor strand of heat resisting alloy passing around both shafts; a track for each reach of said strand on which said strand may slide; a first power transmission for driving the shaft at the delivery end of said strand; a ,second power transmission for delivering power to the shaft at the receiving end of said strand ;-means fox-)adjusting the transmission to the receiving end to deliver a predetermined force or torque; and automatic means for maintaining said force or torque constant.

4. High temperature equipment comprising a hot chamber; transverse shafts at the Iends thereof; an endless conveyor strand of heat resisting alloy passing around both shafts; a track for each reach of said strand on which said strand may slide; a first power transmission for driving the shaft at the delivery end of said strand; av second power transmissionl for delivering power to the shaft at the receiving end of said strand; and means for adjusting the transmission to the receiving end to deliver a predetermined force or tor ue.

5. igh temperature equipment compris- `ing a hot' chamber; transverse shafts; an endless conveyor strand of heat resisting a1- loy extending across said chamber and passing around both shafts; a track for the upper reach of said strand on which said strand may slide; a first power transmission for driving the shaftat the delivery end of said strand; ai second power transmission for delivering power to the shaft at the receiving end of said strand; and means for adjusting the transmission to the receiving end to deliver a predetermined force or torque.

6. High temperature equipment comprising a hot chamber; transverse shafts inside said chamber at the ends thereof; an endless conveyor strand of heat resistingy alloy passing around both shafts; a track for the upper reach of said strand on which said strand may slide; a first power ftransmission for driving the shaft at the delivery end of said strand; a second powertransmission for de- 65 livering power to the-'shaft at the receiving 4end of said strand; 'and means for adjustfor exerting tension on said-strand at the delivery end of'said load carrying reach to pull said reach and the load thereon throu h said chamber; additional transmission or delivering power to said strand at the receiving end of said reach; and an automatic load control means for said additional transmission for maintaining the power delivered at the receiving end sufficient to carry all lthe strand load up to that point, plus an additional increment to push on said load carrying reach at the receiving end.

8. High temperature equipment comprising a hot chamber; an endless conveyor strand l/ofheat resisting alloy having a loadcarry.

ing reach in said chamber; power means for exerting tension on said strand at the delivery end of said load carrying reach to pull sa id reach and the load thereon through said chamber; additional transmissionk for delivering power to said strand at the receiving end of said reach; and means for adjusting said additional transmissipn to carry all the strand load up to that point, plus an additional increment to push on said load carrying reach at the receiving end.

. 9. High temperature equipment comprismg a hot chamber; transverse shafts inside said chamber at the ends thereof; an endless conveyor strand of heat resisting alloy passing around said shafts; a track for the upper-` reach oflsaid strand on which said strand may slide; a first power transmission for y driving a shaft at the delivery end of said strand; a second power transmission for delivering power to a shaft at the receiving end of said strand; means for yadiusting the transmission to the receiving end to deliver a predetermined force or torque, and means for varying the. distance between the shafts to take up slack without interfering. with said torque adjustment. y

10. High temperatureequipment comprising a hot chamber; transverse rshafts inside said chamber; an endless conveyor strand of heat resisting alloy passing around both shafts; a track for the upper reach of said strand on which said strand may slide; a

first power transmission for driving a shaft at the delivery end of said strand; a second power transmission for delivering power to a shaft at the receiving end of said strand; means for adjusting the transmission lto the receiving end 'to deliver a predetermined force or torque; and means for varying the distance between the shafts to take up slack Without interfering with said torque adjustment.

l1. High temperature equipment comprising a chamber; an endless conveyor strand of heat resisting alloy having a load carrying reach extending longitudinally of said chamber; means acting on said strand for pulling said strand along; and additional means engaging said strand at a point back of said first means for pulling on said strand to lessen the load on said first means.

. 12. High temperature equipment comprising a heated chamber, movable conveyor' means inside said chamber, movable conveyor meansoutside said chamber, said chamber.v

having a heat retaining Wall between' the reach of said chain.

necting said sprockets, and yielding take-up means in the tension or ,load transmitting 14'n High temperature. equipment for operation above 1400o F.,comprising refrac- A tory and insulating walls defining a single unobstructed enclosure in the shape of a rectangular parallelo-piped transverse support and drive shafts near the ends of said enclosure having reduced ends` passing out through said Walls, an endless conveyor driven. and 1n part supported by said shafts, skids partly supporting both reaches of said conveyor, and cross bars mounted in said s1de Walls'and supporting atv least one o'f said skids, positive drive means for ro-V, tating the shaft at the discharge end of the conveyor, and automatic means for deliver- 'ing to the shaft at the receiving end of the conveyor a predetermined torque independent of speed and less than that necessary to move the entire conveyor.

15. High temperature equipmentfor operation above 1400o F., comprising refractory and insulating Walls defining asingle unobstructed enclosure, transverse shafts near the ends of said enclosure having reduced ends passing out through said Walls, an endless conveyor driven by said shafts, positive drive means for rotating'the shaft at the dischargeend of the conveyor, automatic means for delivering to the shaft at the receiving end of the conveyor a predetermined torque,

independent of speed and less than that nec"- essai-y to move the entire conveyor, means for adjusting the tension of the conveyor as a whole, and means for adjustingthe torque delivered to the shaft at the receiving end.

16. High temperature equipment for operation above 1400o F., comprising refractory and insulating Walls defining a slngle unobstructed enclosure, transverse shafts near the ends o f said enclosure having reduced ends passing out through said walls, an endless conveyor driven by said shafts, positive drive means for rotating the shaft at the discharge end of the conveyor, automatic means for delivering to the shaft at the receiving end of the conveyor a predetermined torque independent of speed and less than that necessary to move the entire conveyor, and means for'adjusting said automatic means to vary the torque. 17. High temperature equipment for operation -above 1400o F., comprising refractory and insulating Walls defining a single'unobstructed enclosure, transverse shafts near the ends of said enclosure having reduced ends passing out through said Walls, any endless conveyor driven by said shafts, positive drive means for rotating the shaft at the discharge end of the conveyor, and automatic means for delivering to the shaft at the receiving end of the conveyor a predetermined torque independent of speed and less vthan that necessary to move the entire conveyor.

18. High temperature equipmenttfor operation above 1400 F., comprising refractory and insulating Walls Adefining a single unobstructed enclosure, transverse support and drive shafts near the ends of said enclosure having reduced l, ends passing out through said side walls, an endless conveyor driven and in part supported by said shafts, skids partly supporting bothreaches of said conveyor, and. cross bars mounted in said side Walls and said skids. i

f19. High y.temperature equipment comprising'an enclosed chamber hotter-than 1,400 F. and interiorly unobstructed so. that the supporting at least one of A gaseouscont'entscmprise one substantially unitary and uninterrupted mass,.an endless oonveyo'rntirely enclosed in -said chamber, said conveyor itself constituting the main obstruction in said chamber, a skid supporting the upper load-carrying reach of said conveyor, cross bars mounted in the chamlivering to the drive shaft at the receiving endof said conveyor a given torque 'independent of speed and less than that necessary to move the entire conveyor, said transmission belng driven from sald same power means.

20. High temperature equipment comprising an enclosed chamber hotter than 1,400 F. and interiorly obstructed so thatv the gaseous contents comprise one substantially unitary and uninterrupted mass, an endless con- Veyor entirelyenclosed in said chamber, said conveyor itself constituting the main obstruction in said chamber, a skid supporting the upper load-carrying reach of said con- Veyor, cross bars mounted in the chamber Walls and supporting said skid, and a similar skid for the lower slack reach of said conveyor,

In testimony whereof I hereuntotafixgpy I signature.

FRANK A. FAHRENWALD. 

